package cn.orange.ch10_dynamicprogramming;

/**
 * LC115.不同的子序列
 */
public class LC115 {
    public int numDistinct(String s, String t) {
        int m = s.length();
        int n = t.length();
        //dp[i][j]:以i-1结尾的s中以j-1结尾的t出现的次数为dp[i][j]
        int[][] dp = new int[m + 1][n + 1];
        for (int i = 0; i <= m; i++) {
            dp[i][0] = 1;
        }
        for (int i = 1; i <= m; i++) {
            for (int j = 1; j <= n; j++) {
                if (s.charAt(i - 1) == t.charAt(j - 1)) {
                    dp[i][j] = dp[i - 1][j - 1] + dp[i - 1][j];
                } else {
                    dp[i][j] = dp[i - 1][j];
                }
            }
        }
        return dp[m][n];
    }

    public static void main(String[] args) {
        LC115 alg = new LC115();
        System.out.println(alg.numDistinct("rabbbit", "rabbit"));
        System.out.println(alg.numDistinct("babgbag", "bag"));
    }
}
